English

Property $(T_{L^{\Phi}})$ and property $(F_{L^{\Phi}})$ for Orlicz spaces $L^{\Phi}$

Group Theory 2015-08-24 v3

Abstract

An Orlicz space LΦ(Ω)L^{\Phi}(\Omega) is a Banach function space defined by using a Young function Φ\Phi, which generalizes the LpL^p spaces. We show that, for a reflexive Orlicz space LΦ([0,1])L^{\Phi}([0,1]), a locally compact second countable group has Kazhdan's property (T)(T) if and only if it has property (TLΦ([0,1]))(T_{L^{\Phi}([0,1])}), which is a generalization of Kazhdan's property (T)(T) for linear isometric representations on LΦ([0,1])L^{\Phi}([0,1]). We also prove that, for a Banach space BB whose modulus of convexity is sufficiently large, if a locally compact second countable group has Kazhdan's property (T)(T), then it has property (FB)(F_{B}), which is a fixed point property for affine isometric actions on BB. Moreover, we see that, for an Orlicz sequence space ΦΨ\ell^{\Phi\Psi} such that the Young function Ψ\Psi sufficiently rapidly increases near 00, hyperbolic groups (with Kazhdan's property (T)(T)) don't have property (FΦΨ)(F_{\ell^{\Phi\Psi}}). These results are generalizations of the results for LpL^p-spaces.

Keywords

Cite

@article{arxiv.1503.00835,
  title  = {Property $(T_{L^{\Phi}})$ and property $(F_{L^{\Phi}})$ for Orlicz spaces $L^{\Phi}$},
  author = {Mamoru Tanaka},
  journal= {arXiv preprint arXiv:1503.00835},
  year   = {2015}
}